After the battery is used for a period of time, some active materials will inevitably sink. If the active materials are not activated in time, it will inevitably have some impact on the capacity of the battery. Therefore, when the electric vehicle is frequently used, it is necessary to treat the battery every season. Discharge deeply once. The maintenance-free battery will generate heat during charging and high-current discharge. When there is heat, water will evaporate. Although the process of water evaporation is very slow, over time, the cumulative amount of water evaporation cannot be underestimated. Therefore, the battery should be filled with water every 6 months or so, so that the service life of the battery will be prolonged. Lead-acid batteries have no memory, so the rapid decrease in capacity is mainly due to the vulcanization of the battery and the 'loss of water' and 'loss of electricity'. The most feared of the battery is the 'loss of electricity' and undervoltage. The plate is extremely easy to be injured. In reality, up to 70% of the electric vehicle battery capacity is reduced due to the strong current (starting current) when the electrode plate is discharged (especially obvious electric friction). The electrode plate strain is a physical damage to the battery. The damage cannot be repaired. When the battery is not used for a long time, charge the battery at least once a month. The purpose of this is to prevent the battery from being stored for too long and causing the battery to vulcanize and 'loss of electricity'.